1. Field of the Invention:
The present invention relates to a method for drying coals, particularly coking coals, by using a heating medium for exchanging the sensible heat of a gas generated from coke ovens and using this heat medium containing the sensitive heat as a main heat source for the drying.
2. Description of Prior Arts:
In coke ovens in which coking coals are distilled to produce cokes, the oven gas generating during the distillation in carburization chambers passes through ascension pipes to bend pipes communicating with dry mains and the gas is cooled in the bend pipes by a liquor spray with ammonia liquor, then the oven gas collected in the bend pipes is further cooled down to about ordinary temperatures by gas coolers. The gas generated from the coke ovens is usually at a temperature ranging from 600.degree. to 800.degree. C., but due to the lack of efficient means for recovering the heat contained in the oven gas, or due to a failure in finding appropriate applications for the recovered heat from the oven gas, no practical trials have been made for recovering the waste heat of the coke oven gas.
Meanwhile, in coke ovens, combustion chambers provided adjacent the carbonization chambers and gaseous fuels are burnt therein for the purpose of distillation of coking coals, and only part of the waste gas generated by the combustion is recovered in heat regenerating chambers and the remainder is not utilized in the conventional arts.
The present inventors have made extensive studies and experiments for recovering the sensible heat contained in coke oven gases from the point of energy savings and proposed a method as disclosed in Japanese Patent Application Laid-Open No. Sho 55-40736, according to which a heat-stable organic heat medium, such as alkyldiphenyl, having a high boiling point, high fluidity at low temperatures, and being usable as liquid under ordinary pressure is supplied through heat conductive pipes arranged in the inside wall of ascension pipes of coke ovens to recover the sensitive heat of coke oven gases and utilize this recovered heat for pre-heating the combustion gas for hot blast ovens.
The method just mentioned above has been found to be very effective to recover the heat at a high recovery ratio.